Island



(Model) B. I. FROST. Switch Board for Electric Circuits. No 236,884. Patented Jan. 25, 1881.

Witnesses:

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Inventor: I

UNITED STATES PATENT OFFICE.

. ELLIS F. FROST, OF PAVTUOKET, RHODE ISLAND, ASSIGNOR OF ONE-HALF TO CHARLES H. M. BLAKE, OF WESTON, MASSACHUSETTS.

SWITCH-BOARD FOR ELECTRIC CIRCUITS.

SPECIFICATION formingpart of Letters Patent No. 236,884, dated January 25, 1881.

Application filed September 13, 1880.

To all whom it may concern Be it known that I, ELLIS F. FRosT, of Pawtucket, in the State of Rhode Island, have invented a new and useful Improvement in Switch-Boards for Electric Circuits, of which the following is a specification.

The object of the invention is to make it impossible for the operator using the switchboard at a central station to connect more than two lines or independent circuits in one grand circuit.

The invention consists in using upon the board for each circuit a number of contactpoints, one less in number than the number of 1 independent lines or circuits represented on the board, and connecting by wire each con-,

tact-point in each circuit with one contactpoint, and one contact-point only, in one other circuit, any ordinary device being used for connecting the independent lines or circuits with either of its own contact-points upon the board.

Inthe drawings I have represented a switchboard as constructed for use with five inde- 2 pendent electric circuits, any two of which are to be connected without the possibility of brin ging in a third.

Figure l is afront elevationof my improved switch-board. Fig.2 is a side elevation of the 0 same. Fig. 3 is a rear elevation of the same. Fig. 4 is a diagram illustrating the circuits, and especially showing the connections by wire between the contact-points upon the switchboard. Fig. 5 is a diagram, hereinafter ex- 5 plained. Fig. 6 illustrates a modification of the switching mechanism.

v A is a plate, of wood or other non-conducting substance, erected upon a bed, B, and containing a number of slots, S S S S S, equal to the number of circuits controlled by the switch-board. Each slot S, S S S and S has a number of brass-lined notches, one less in number than the number of circuits controlled by the board-that is, in the board shown there are five slots, and each slot contains four brass-lined notches or contactpoints. Each series of notches is numbered as shown, there being in each series, however, no number corresponding to the number of the (ModeL) slot to which the series belongs-that is, slot S contains no notch marked 1, slot S contains no slot marked 2, 8:0.

Connections between the notches or contactpoints upon the board are made by wires, as represented by dotted lines in Fig. 4. A wire connects each notchv or contact-point of each series with one notch or contact-point, and with one only, of one other series, as shown, and accordingly each notch is connected but with one other notch.

.O O are two wooden uprights, supporting a cross-bar, D, of llOIl-GOllllllCtlll g material, to which are hinged several brass rods or levers, R R R R R equal in number to the number of slots, and consequently to the number of circuits. Each lever is connected, by a wire, 1010 20 10* 10 with an independent line or circuit.

Each slot upon the board has, as shown, a brass lining, a a c a (4 at its head, connected, by wire 9 g g g g with ground through such independent electric apparatus as it may be desirable to use at the central office in connection with each circuit.

In the normal condition the brass rods are all elevated, as shown in Figs. 1,2, and 3, and are, respectively, in contact with lining-plates a a a a a The independent circuit represented by slot S is then from ground through the several out-stations of the circuit by wire to to rod R, lining-plate a, and wire g, through independent call or other apparatus to ground. In like manner there is an independent circuit, 20 R a 9 so also 20 R a 9 850.

To connect any two circuits, bring the brass rods belonging to the two circuits each down to that slot of its own series which is connected by wire with aslotin the series belonging to the other rod; or, where the slots and rods are numbered as above directed, bring the rods belonging to the two circuits each down to a notch or contact-point corresponding in number to the number of the other slot. Thus, in Fig. 4, Ihave shown how the second and fourth circuits may be connected. The rod R is brought down to notch a in the slot S and the rod It is brought down to notch 2 in. slot S. An inspection of Fig. 4 will show that no other rod can break in upon the connection thus established, and that the second and fourth circuits can be connected in no other way.

The ground-connection at the central ofiice in each independent circuit is broken when the rod of that circuit is lowered from the liningplate a (H, &c., at the head of the slot belongin g to the circuit.

It is obvious that other means might be employed for establishing metallic connection between any independent circuit and either of the several contact-points belonging to that circuit without departing from my invention. For instance, as illustrated in Fig. 6, the wire '10 might be attached to metallic slide traveling up and down upon a rod in close proximity to the line of notches or contact-points, and having a turning motion, which could bring a metallic projection from the traveling slide in contact with the notch or contact-point; or the rod upon which the metallic slide travels may be of brass, with the wire w attached to it; but the means for establishing metallic connection between the independent circuits and their respective several contact-points upon the board form no part of my invention, except when used in combination with a switch-board containing contact-points arranged in series and connected as above described.

It is obvious, further,that an indefinite number of circuits may be represented upon my improved switch-board, each circuit having a number of contact-points, one less than the number of circuits represented.

In practice I place all the contact-points having the same number in a single row across the board, leaving a vacant space at the place Where the number of the contact-points would be the same as the number of its own slot or series, it being more convenient for the operator to always bring his lever or slide to one level for a required number. This is illustrated in the diagram at Fig. 5, where the perpendicular rows represent the several series of contact-pointsand circuits, the rings being contact-points and the filled disks dead-points.

I claim- 1. A switch -board provided with several slots, each of which contains a series of brasslined notches, each notch in each slot being in metallic connection with another notch, and but one other notch, and that in another slot, substantially as described, for the purpose specified.

2. A switch-board provided with several slots, each of which contains a series of brasslined notches, each notch in each slot being in metallic connection with one, and but one, other notch, and that in another slot, in combination with a number of line-circuits equal to the number of slots, and brass levers connected with said line-circuits and working in said slots, substantially as described, for the purpose specified.

3. A switch -board provided with several slots, each of which contains a ground-plate and a series of brass-lined notches, each notch in each slot being in metallic connection with one, and but one, other notch, and that in another slot, in combination with line-circuits and brass levers connected with said line-circuits and working in said slots, substantially as described, for the purpose specified.

4. A switch-board containing several series of contact-points, the number of contact-points in each series being one less than the number of series, and each contact-point being in metallic connection with one, and but one, other contact-point, and that in another series, substantially as described, for the purpose speci- 5. A switch-board containing several series ofcontact-points, the number of contact-points in each series being one less than the number of series, and each contact-point being in metallic connection with one, and but one, other contact-point, and that in another series, in combination with line-circuits, one for each series of contact-points, and suitable mechanism for connecting each line-circuit or disconnecting it from any contact-point in the series to which the line-circuit belongs, substantially as described, for the purpose specified.

ELLIS F. FROST.

Witnesses:

W. W. SWAN, H. G. OLMSTED. 

